An electrostatic precipitator is commonly used to remove fine particulate matter from a gas stream. An electrostatic precipitator is commonly used in the power generating industry to remove particulate from combustion products from a boiler before gaseous products of combustion enter a smokestack. There are also a wide variety of other uses for removing particulate produced in an industrial process, such as, in a paper mill, cement plant, chemical plant, or a steel plant. A conventional and well known construction for electrostatic precipitators is one which includes a plurality of large flat steel plates. Each of the plates typically has a length of twenty feet or more and has a width of six feet or more. The plates are hung from supports with the length of each plate being in the vertical direction. The plates or panels or curtains as they are sometimes called are equidistantly spaced from each other and are parallel to each other. Each plate also has a plurality of stiffeners which extend the length of the plate to keep the respective plate flat. A plurality of electrodes is positioned between adjacent plates. The electrodes typically are wires which are hung from a frame and extend the entire length of the plates. Other devices are used for electrodes in lieu of wires, such as, pipes with sharp nails attached, coiled wire, metal rod, flat wire with or without barbs, and a variety of other constructions, all of which share the common feature of a sharp point. Ordinarily, when wires are used, weights are hung on the bottom of the wires and the movement of the weights is restrained in some manner to eliminate undue swaying of the wire. A housing encloses the plates and the wires. The housing is connected to the source of gaseous material with particulate and opens into a conventional conduit for carrying away the exhaust gaseous material such as a smokestack.
The gaseous material with particulate matter flows between the plates across the surface of the plates. The wires are electrically charged with one charge so that the particulate matter carried by the gaseous material becomes charged and is attracted to the plates which are charged with a charge opposite to that of the charge on the wires. The charged particulate matter collects on the plates and is held onto the plates by the charge on the plates. Thus, the gaseous material passes the plates and has the particulate matter removed therefrom.
In a typical operation of an electrostatic precipitator, the particulate matter collected on the plates is intermittently removed from the plate. The plates are vibrated in some manner, such as, being rapped with a hammer to dislodge the particulate matter from the plates. The particulate matter falls from the plate to the bottom of the electrostatic precipitator housing. A typical construction of a housing includes openings in the bottom thereof through which the collected particulate matter is removed from the housing for disposal.
It has been found that after prolonged usage of the precipitator, especially when hot gases flow through the precipitator, the plates lose their flatness in that they become warped or bent. This warping or bending of the plates has a deleterious effect on the effectiveness of the electrostatic precipitator. Typically, a given plate will warp or bend sufficiently so that the plate contacts one or more wire electrodes, thereby shorting out the wire electrodes and thus rendering the wire electrodes ineffective. Thus, particulate matter passing the wire electrodes is not charged by the wire electrodes. The uncharged particulate matter is not attracted to the plates so that the particulate matter is carried out of the housing rendering the precipitator ineffective.
There are a number of known devices for straightening plates once the plates have become warped or bent. U.S. Pat. No. 4,478,614, issued Oct. 23, 1984, to John A. Jonelis entitled, "Electrostatic Precipitator Construction Having Spacers" discloses several spacer constructions which are positioned between plates to straighten the plates. U.S. Pat. No. 4,479,813, issued Oct. 30, 1984, to John A. Jonelis entitled, "Electrostatic Precipitator Having Ladder Bar Spacers" discloses other spacers used for straightening warped or bent plates. U.S. Pat. No. 4,559,064, issued Dec. 17, 1985, to Anthony J. Ahern entitled, "Electrostatic Precipitator Having Spacers" teaches spacer constructions which are positioned between plates for straightening bent or warped plates. U.S. Pat. No. 4,647,296, issued Mar. 3, 1987, to Morris B. Tuck entitled, "Spacers For Straightening Warped Precipitator Curtains" teaches a spacer construction used for positioning a spacer between precipitator plates or curtains to straighten the plates. All of the aforementioned patents are directed to spacer constructions which are used between adjacent plates.
It has been found that the aforementioned spacers are most effective when the distance between adjacent plates has been decreased from the original spacing because the plates are bowed toward each other. When the last plate of a group of plates is bowed away from its adjacent plate and toward the housing, it is difficult to achieve an effective straightening of that last plate by utilization of the spacers which are designed for being positioned between adjacent plates. U.S. Pat. No. 4,007,023, issued Feb. 8, 1977, to Willi Batza, et al., entitled, "Electrostatic Precipitator With Collector-Electrode Spacers" is directed to an electrostatic precipitator construction wherein a spacer is disclosed for use with a housing wall and a plate; however, this spacer construction requires that the plate be spaced from a housing wall a given distance to be effective and does not lend itself to moving a plate from a wall. Batza's spacer construction is designed for inclusion when the electrostatic precipitator is originally built rather than installing spacers after the plates have become bent or warped.
There are a number of known constructions which show an electrostatic precipitator plate connected to a housing. One of such disclosures is U.S. Pat. No. 1,600,496, issued Sept. 21, 1926, to Weiskopf, entitled, "Apparatus For Electrical Precipitation Of Suspended Material From Gases". U.S. Pat. No. 2,036,323, which issued Apr. 7, 1936, to Engert, entitled, "Box Collecting Electrode For Electrical Precipitators" discloses a box construction having movable side walls. U.S. Pat. No. 2,195,431, which issued Apr. 2, 1940, to Shively et al, entitled, "Gas Treating Apparatus" discloses plates connected to a housing wall. U.S. Pat. No. 2,347,709, which issued May 2, 1944, to Penney, entitled, "Electrical Dust Precipitator" also discloses plates connected to a housing. U.S. Patent No. 2,705,221, which issued Mar. 29, 1955, to Clark et al, entitled, "Electric Filter" teaches a construction wherein the plates are connected to a housing. U.S. Pat. No. 3,086,341, which issued Apr. 23, 1963, to Brandt, entitled, "Shaking Device For Electric Filters And A Method For Operating Same" shows a construction wherein plates are connected to an anvil which is connected to a housing. U.S. Pat. No. 3,748,831, which issued July 31, 1973, to Lagerdahl et al., entitled, "Device For Electric Precipitator" discloses a device wherein plates are connected to a housing. U.S. Pat. No. 3,803,809, which issued Apr. 16, 1974, to Gelhaar et al, entitled, "Electrostatic Precipitator" teaches plates connected to the housing on the ends of the plates. British Publication No. 1,099,342, entitled, "Improvements in or relating to Electro-Precipitators" shows plates connected to the side wall but at the ends of the plates. None of the foregoing disclosures teaches or even suggests the concept of an adjustable buttress which engages a housing of an electrostatic precipitator and is used to move a bent or warped plate into its proper attitude thereby straightening the plate and to hold the plate in that position.